Heretofore, as a steam cooker for cooking an object to be heated such as food by using steam, there is a one that feeds superheated steam into an oven (see JP 8-49854 A). This steam cooker has a steam generator in which a heater is provided in a pot to generate steam, and a steam superheater that generates superheated steam by heating the steam generated by the steam generator, and the superheated steam generated by the steam superheater is sent into the oven to cook food.
With this steam cooker, cooking by steam is carried out by first performing preheating operation for raising the inner temperature of a heating chamber to a specified temperature, thereafter with the cooking object set into the heating chamber, switching the operation mode to a cooking operation so that steam generated by the steam generator is heated by the steam superheater and supplied to the heating chamber. However, with this steam cooker, since the heater of the steam generator is turned on after the switching to the cooking operation, it takes time for the water temperature in the steam generator to rise, causing a slow start-up of the steam supply to the interior of the heating chamber, disadvantageously.